Can magnetic field expand faster than light?

[Dale]

Yes, this is the principle used by the ill-fated sharper image "ionic breeze". You can use that principle to build a little hovercraft called an http://en.wikipedia.org/wiki/Ionocraft" . The thrust that these generate is currently not enough to lift the high voltage power supply that they need, but I think that is probably a practical limitation rather than a fundamental one. They make good little science fair projects.

 

[Tominator]

I have heard about the Ionocrafts, but I assume, they do not use plasma. I was thinking about creating plasma by the EM field and thus making a kind of EM jet engine. Because the plasma will be generated only by using electricity and of course the air, there will be no need for fuel while in the atmosphere. On the other hand, this concept would be even more inefficient than rockets.

Is there an ionizator used in the ionocrafts?

I thought, that if ionized gas runnig around in the nozzle in the direction from the air-intake to the part, where air is exhausted was used there, than the ionized gas can make the air accelerate. The ionized gas would not be exhausted, it would only circle around grabbing some air with and accelerating it in the right direction. Would this be more efficient than today's ionocrafts?

 

[Dale]

Well, the word "plasma" isn't well defined to my knowledge. A plasma is a partially ionized gas, and an ionocraft does partially ionize the air, but the degree of ionization is so low that it doesn't have much of the "collective" behavior typical of more completely ionized plasmas.

I don't know about the efficiency of the circulating nozzle idea. You could certainly keep the ions in the nozzle longer and so perhaps get more ionization for the same ionization current, but I am not clear about how you would turn the circulation into thrust.

 

[Tominator]

Well, the word "plasma" isn't well defined to my knowledge. A plasma is a partially ionized gas, and an ionocraft does partially ionize the air, but the degree of ionization is so low that it doesn't have much of the "collective" behavior typical of more completely ionized plasmas.

I don't know about the efficiency of the circulating nozzle idea. You could certainly keep the ions in the nozzle longer and so perhaps get more ionization for the same ionization current, but I am not clear about how you would turn the circulation into thrust.

I was counting with air as a propellant. The air will be sucked in, thanks to circulation of ionized gas, then compressed and accelerated out of the nozzle. (also by the circulation) So no energy would be wasted on creating plasma. It should work like a propeller made out of gas. Would it work?

 

[Dale]

I don't know. I am having a hard time visualizing how the circulating ions would act like a propeller. I am afraid that you will have to work this one out yourself, but I can also tell you that plasma mechanics is an incredibly advanced subject. To really learn it will literally take years of serious effort.

 

[Tominator]

Anyway, thanks for all the answers

 

[Dale]

You're welcome!